Process for forming textiles on heat degradable backings



United States Patent C) 3,438,107 PROCESS FOR FORMING TEXTILES ON HEAT DEGRADABLE BACKINGS Eugene Gula, Rutherford, and Stanley E. Ross, Passaic, N.J., assignors to J. P. Stevens & Co., Inc., New York, N.Y.. a corporation of Delaware No Drawing. Filed Aug. 30, 1965, Ser. No. 483,831 Int. Cl. D02g 1/16; D04h 17/00 US. Cl. 2876 11 Claims ABSTRACT OF THE DISCLOSURE A method of preparing textile base materials comprising combining a heat-degradable thermoplastic support material With a non-support textile material having a degradation temperature above that of the support material, and thereafter heating the combined materials for a time and at a temperature suificient to degrade said support material, while leaving said textile material intact.

This invention relates to the use of polyolefin yarns in backing or support materials for textiles. More particularly, it relates to the preparation of a heat-degradable backing material suitable for usage as a base cloth in lace manufacture.

It is common practice in the textile industry to employ a backing or support for textiles which do not of themselves posses sufiicient strength to Withstand the rigors of fabric processing. Thus, in the manufacture of lace, the

laces are stitched upon a suitable backing material, with the backing subsequently being removed after the lace has been processed. A variety of materials for backings and a number of methods for removing the same have heretofore been employed in the textile industry.

Base fabrics have been prepared from fibers of polyvinyl alcohol, silk or alginate, these materials subsequently being dissolved in alkali solutions. Base fabrics have also been prepared by using treated cotton crinoline. Although the base fabrics hitherto employed have proved useful, they nevertheless each exhibit serious shortcomings. Silk, polyvinyl alcohol and alginate fibers require prolonged and/or strong wet alkali treatment in order to undergo dissolution. These fibers are also quite expensive for such commercial operations. Treated cotton backings (crinoline) require a relatively high concentrated alkali treatment for dissolution. Embroidery crinoline also exhibits the disadvantage of rapid deterioration under normal storage conditions. In addition to the aforedescribed failings, some backing fabrics leave a residue on the lace surface 'Which is extremely difficult to remove from the lace.

It is an object of this invention to provide an economical base support for textile materials which may be eliminated without detrimentally aifecting the textile material.

Another object of this invention is to provide a method for removing a supporting base material from a textile material which does not involve stringent chemical treatment.

Other objects and advantages of this invention will be apparent from the description that follows hereinafter.

'In accordance with this invention, a base support material for a textile material is prepared from a polyolefin which is subsequently eliminated by heat treatment at elevated temperatures. The support material is preferably a woven, knitted, or bonded fabric, but it could also be a cast, molded, extruded, or formed structure such as a film or a lattice. A fabric support is most suitable since such a structure provides a greater surface area for subsequent degradation.

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For the purposes of this invention, the polyolefin support material is preferably polypropylene, poly (4-methyll-pentene), or a polymer of similar structure. Also, the support material may contain an agent which serves to accelerate the degradation of the polymer. It should be noted that, although the discussion that follows is concerned with lace manufacture, the present invention is applicable to the preparation of any textile material requiring the use of a supporting fabric or scaffolding thread. For purposes of convenience, the following discussion will also be limited to the use of a polypropylene support fabric.

In employing the base fabrics of this invention, any conventional method of lace manufacture may be utilized. Thus, for example, a lace structure is stitched upon a polypropylene backing by a Schifiii lace machine and the resulting composite is passed through an oven or other suitable heat treatment means wherein the backing is disintegrated. Any backing residue which may remain after the heat treatment can be readily removed by blowing, shaking, vacuum, or like means.

In the practice of this invention, it is preferred that a degradation accelerating agent be incorporated in the polypropylene backing. Such an agent may be added at any stage of fabric manufacture, that is, incorporated into the polymer and extruded within the molten filaments, on the yarns before they undergo Weaving, or on the backing after it has been woven into a fabric.

As was mentioned previously, it is preferred that a degradation accelerating agent be incorporated in the polypropylene backing. Careful selection of such an agent must be made since a given compound may exhibit a Wide range of degradative activity depending on the chemical nature of its environment and on its concentration in a given environment. Since a very slight change in environmental conditions may either destroy or enhance the degradative activity of the agent, it is difiicult to set forth any comprehensive criteria for choosing the proper agent. In general, any agent that enhances the thermal oxidation or deterioration of polypropylene may be used in the textile supports of this invention. Among the compounds that accelerate the thermal degradation of polypropylene may be included copper and copper-containing compounds, compounds containing iron or cobalt, certain organic halogen compounds, and certain metallic salts of organic acids. Examples of the degrading agents include finely divided copper, cupric oxide, copper stearate, copper oleate, copper ethyl acetoacetate, copper linoleate, colbalt acetylacetonate, cobalt stearate, cobalt oleate, ferric acetylacetonate, cupric acetylacetonate, carbon tetrachloride, chloroform and methylene chloride. Also, copper-containing dye fixatives have proven effective in accelerating the decomposition of polypropylene backing fabrics. Examples of these fixatives include: Standye Fix D (Standard Chemical Products, Inc.), Cuprofix (Sandoz, Inc.), and Coprantex B (Ciba Chemical and Dye Company). It should be noted that, although backing fabrics can be prepared from polypropylene yarns untreated with a heat degrading agent, especially eifective results are achieved by employing yarns so treated.

The amount of heat degradation accelerator employed in the textile backings of this invention varies with several factors. The type of accelerator being utilized will affect the concentration of the accelerator, since some accelerators possess a higher degradative activity than others and consequently a smaller quantity of the agent will suflice. The concentration of degradative agent is further dependent upon the presence of stabilizing compounds in the polypropylene. Often commercial polypropylene yarns contain light and/or heat stabilizers and accordingly a larger amount of degradative agent must be employed to counteract the action of these stabilizers. The step in the process of fabric manufacture at which the degradative agent is added similarly affects the concentration of the agent. Considerably less additive is required if it is added to the polypropylene before the filaments are extruded than would be required if the additive were added to the spun yarns or to the woven fabric.

The degradation accelerator is preferably employed in a concentration of up to about 5%, by weight, of the polypropylene. Of course, amounts of accelerator greater than the indicated range can be utilized, but increased concentrations of the accelerator provide little advantage over the preferred quantities and, in fact, it has been noted in some cases that an excess of the accelerator will inhibit its degradative activity. It should be noted that the accelerator may be applied to the polypropylene yarn or fabric by any conventional technique such as by dipping, spraying, padding, and the like.

The duration and temperature of the degradation treatment of the base fabrics of this invention will vary with the melting point of the polyolefin, with the denier and number of filaments in the yarns of the backing, with the construction of the base, with the amount of degradation accelerators (if any) present in the backing, and with the amount of heat or light stabilizer which may be present in the polyolefin yarn. More rapid degradation of the polyolefin occurs when the yarns do not contain any stabilizing agents. Thus, for example, heat and/ or light stabilized polypropylene may have an oven life of 12-18 hours at 300 F. compared to the life of the untreated polypropylene of about /21 hour at the same temperature. In general, a lace having a polypropylene backing containing no accelerator and no heat or light stabilizer may be treated at temperatures ranging from about 250 F. to about 330 F. (the melting point of the polymer) for from about 2 hours to about 30 minutes for satisfactory results. A lace having a polypropylene backing treated with a heat degradative agent requires temperatures of from about 250 F. to about 330 F. for such extremely short periods as within about minutes.

The base fabrics of this invention may be prepared in any conventional manner, such as by weaving, knitting, bonding, etc. The only requirement of the base fabric construction is that it possess sulficient strength to support lace stitching and to undergo processing. Any of the usual finishing operations, e.g., bleaching or dyeing, may be carried out on the embroidered fabric before heat treatment.

In summary, then, the support fabrics of the present invention possess inherent advantages over fabrics heretofore used in the textile industry. Whereas previously employed backing fabrics required wet and/ or strong chemical treatment, the present fabrics do not entail usage of any treatment which might harm the embroidered lace. The fabrics of the invention are also relatively inexpensive and posses sufficient stability for storage. Moreover, since most finishing plants already have drying and curing ovens, the process of this invention can be carried out on existing equipment.

The following examples will further illustrate the embodiments of this invention.

EXAMPLE I Unstabilized pellets of polypropylene (Molecular Weight=225,000) were melt spun at 535 F. to an undrawn yarn of 115/10 and drawn to 30/10 yarn using conventional melt spinning and drawing equipment. The polypropylene yarns were woven into a fabric and cotton threads were stitched thereon by a conventional Schifili lace machine. The resulting combination of lace and polypropylene support fabric was then passed into a circulating air oven maintained at a temperature of 300 F. After 30 minutes, the polypropylene yarns became brittle and disintegrated, leaving the lace structure intact.

4 EXAMPLE II The procedure of Example I was followed in preparing the polypropylene base fabric except that 1.0%, by weight, of copper acetylacetonate was compounded with the polypropylene in the melt bath. The polymer was converted into a base fabric of 30/10 yarns and a lace structure was stitched thereon. The resulting combination was then passed into a circulating air oven maintained at a temperature of 300 F. After 10 minutes, the polypropylene yarns became brittle and disintegrated, leaving the lace structure intact.

EXAMPLE III Unstabilized 30 denier, 10 filament polypropylene yarns were knitted into tubing for heat degradation testing. This tubing disintegrated after heating at 300 F. for 4045 minutes. Tubing of the same characteristics were padded with approximately 4%, by weight, of copper-containing fixatives, viz., Standye Fix D, Cuprofix and Coprantex B. The tubing containing the copper-containing compounds each disintegrated after heating at 300 F. for 10 minutes.

EXAMPLE IV Unstabilized polypropylene pellets of molecular weight 180,000 were melt extruded along with the various heat degrading agents shown in the table below which had been incorporated into the melt by previous mixing with the polymer pellets. The pellets were converted into /10 yarn at an extrusion temperature of 480 F. and subsequently drawn to 30/ 10 yarn. The drawn yarns were knitted into fabric, embroidered with lace and the backing fabric heat degraded. A heat stabilized polypropylene sample was also comparably treated. The following results were obtained with regard to disintegration of the backing fabric:

Approx. time to de- Oonc. of grade at oven tempera- IIeet degrading agent agent (pertures 01-- cent by wt.)

275 F. 300' F. (min.) (min.)

None (unstabilized polypropylene 0 1 23 30 control) Copper steal-ate 1 20-30 10 Copper acetylaeetonate 0.75 20 10 1. 0 20 10 1. 5 20 1O 3. 0 40 25 5. 0 45 25 10. 0 (i0 30 Cobalt stearate 1 20-30 10 Cobalt oleate 1 15-20 5-7 Ferric acetylacetonate 1 20'30 15 Cobalt aeetylacetonate 1 10-15 4-5 None (heat stabilized polypropylene 1 24 48 1 12-18] 1 Hours.

EXAMPLE V Poly (4-methyl-1-pentene) of approximately 240,000 molecular weight was extruded into 530 denier/34 filament yarn at a temperature of 600 F. The yarn was subsequently stretched at a draw ratio of 3.5 :1 to approximately denier and knitted into fabric. The knitted fabric was embroidered and placed in a circulating air oven at a temperature of 400-410 F. (the melting point of the polymer). After a period of approximately 45 minutes, the fabric had disintegrated and had become embrittled, leaving the embroidered portion intact.

EXAMPLE VI The fabric described in Example V was padded with 2%, by weight, of Coprantex B. The fabric was then exposed to an elevated temperature of 400-410 F. Within a period of 5-10 minutes the fabric had become embrittled and could be separated from the embroidery in powdery form when shaken mechanically.

What is claimed is:

1. A method of preparing a textile material possessing long-term shelf stability comprising:

(a) combining a heat-degradable thermoplastic support material with a non-support textile material having a degradation temperature above that of the thermoplastic support material,

( b) thereafter heating the combined support and nonsupport materials to a temperature above the degradation temperature of said support material but below the degradation temperature of said non-support material, until the thermoplastic support material is removed, leaving the non-support material intact.

2. The process of claim 1 wherein the heat-degradable thermoplastic support material is a polyolefin.

3. The process of claim 2 wherein the polyolefin is polypropylene.

4. The process of claim 2 wherein the polyolefin is poly(4-methyl-1-pentene) 5. The process of claim 1 wherein the heat-degradable thermoplastic support material contains heat degradative agent.

6. The process of claim 5 wherein the heat degradative agent is present in an amount of up to about 5% by weight of polypropylene.

7. The process of claim 6 wherein the heat degradative agent is a copper-containing dye fixative.

8. A method of preparing decorative cotton lace structures comprising embroidering a cotton lace pattern upon a polyolefin textile support material and thereafter heating the emboidered polyolefin support material above the degradation temperature of the polyolefin support material but below the degradation temperature of the cotton lace pattern until the support is removed, leaving the cotton lace pattern intact.

9. The method of claim 8 wherein the polyolefin support material is polypropylene containing a heavy metal heat degradative agent.

10. The method of claim 9 wherein the heavy metal degradative agent is a copper-containing dye fixative.

11. The method of claim 10 wherein the embroidered polypropylene support material is heated between about 250 F. and 330 F.

References Cited UNITED STATES PATENTS 525,738 9/1894 Hauser 2876 2,365,315 12/1944 Williams 2876 2,969,580 l/196l Wyner 2872 3,307,990 3/1967 Homier et al 16181 XR 3,366,529 1/1968 Olson 156-148 XR 337,687 3/1886 Krusi 2876 1,834,339 12/1931 Dreyfus et al. 28-76 FOREIGN PATENTS 255,369 11/1911 Germany.

JOHN PETRAKES, Primary Examiner.

US. Cl. X.R. 874; 2872 

